[jwxr7]

My geo definitly likes to go as slow as is practical in 5th gear. It has pretty low gearing.

There is also the effect of the engine's efficiency curve. Aero load goes up with speed but the engine may also be going towards a more efficient rpm to help offset drag (depending on gearing). I believe my GMC does this on the highway (it has a 5spd manual). It has pretty tall gearing. The scangage seems to average similar FE going either 55 or 65 on the highway. I can only attribute this to having something to do with the engine's efficiency range. Of course anything over 65 causes a decrease in mpg and speeds under 55 return better FE.